Objective : This study investigated the mediating effects of major competency on the association between the major satisfaction and career maturity of occupational students. Methods : The subjects were 177 students who had completed occupational majors at K University. The research period was from September 5 to 20, 2023. Data were analyzed using descriptive statistics, t-test, ANOVA, Pearson's correlation, and hierarchical multiple regression. The statistical significance of the mediating effect was tested using SPSS PROCESS 4.3 Macro using the bootstrapping method. Results : According to the results of this study, the students showed a mean of 4.13 points in their satisfaction with their major, 3.58 points in their career maturity, and 3.71 points in major competency. Statistically significant positive correlations were found between the students'satisfaction with their major, their career maturity, and major competency. In addition, their major competency produced a partial mediating effect on the relationship between their satisfaction with their major and their career maturity and the higher the major competency and career maturity, the higher the major satisfaction. Conclusion : Therefore, it is necessary to revitalize the curriculum that enhances major competency in order to increase major satisfaction.